Fabricating Quantum Devices. Devices fabricated at a scale small enough to respond to quantum-mechanical effects are of interest not only for developing smaller and faster computers, but also for advanced sensors. These devices are exquisitely sensitive to small fluctuations in voltage potential and magnetic field strength, such as those produced by cells and organisms. We are investigating techniques for fabricating and testing such tiny devices, in order to understand which device characteristics are critical to function and which can be compromised to allow ease of fabrication. In the previous year, we used the Nanomanipulator to form 30-nm gaps in gold wire and then repair the gaps, restoring conductivity. We maneuvered a small gold colloid into such a gap (a task that we feel could not have been done without the force feedback present in the Nanomanipulator system). We made external contact to the wire, measuring the resistance changes during manipulation. This past year has been spent preparing technique and gathering equipment for further studies. One difficulty we encountered was with the large amount of gold film we had to remove from our 5 micron-wide wires in order to bring them down to a small enough scale. The material would form large clumps around the site, blocking access to the tip and probably causing a large capacitance at the gap. We have found at IBM a source of 100nm wires, which are much better starting templates for our device fabrication. We have also been specifying and ordering measurement equipment that will be capable of determining the impedance of gaps in the wire without inducing voltages large enough to damage the structure. Once we have a small gap, we will place the device in our liquid helium Dewar and do electron transport measurements. We also plan to insert colloids in the gaps and perform tunneling spectroscopy on them.